A system and method are provided for controlling a data rate in a communication system. A transmitter sets threshold values for classifying Modulation and Coding Scheme (MCS) levels. When receiving information about an MCS level desired to be used in the receiver, the transmitter sets an MCS level to be actually used in the receiver and transmits information about the set MCS level to the receiver. When detecting that the information is to be transmitted to the transmitter, the receiver computes instantaneous link capacity using a channel estimation result, sets an MCS level mapped to the instantaneous link capacity, and transmits information about the set MCS level to the transmitter. The receiver receives the information about the MCS level to be actually used from the transmitter.